Method of and apparatus for hardening surfaces of metal bodies



Feb. 17, 1942. A. B. KINZEL METHOD OF AND APPARATUS FOR HARDENING SURFACES 0F METAL BODIES Original Filed Jan. 19, 19:55

INVENTOR AUGUSTUS B. K NZEL BY 21/ Pk/M) ATTORNEY such cylinders.

Patented Feb. 17, 1942 METHOD OF ANDAPPARATUS FOR HARDEN- n ING SURFACES F METAL BODIES Augustus B. Kinzel, Douglaston, N. Y., assignor, by mesne assignments, to Union Carbide and Carbon Corporation, a corporation of New York Continuationof application Serial No. 2,501, January 19, 1935. Serial No. 218,930

19v Claims.

This invention relates to the hardening of surfaces of metal bodies, and more particularly to the hardening of cylindrical surfaces of metal bodies, such as the inner walls of cylinders of internal combustion engines. This application is a continuation of my application Serial No. 2,501, filed January 19, 1935.

Wear on the inside surface of the usual cast iron cylinders has long been one of the limiting factors in the life of internal combustion engines. Attempts have been made. to increase the wear resistance .by the use of liners, or by nitriding or carburizing the insidesurfacesof harden the surface of the inner walls ofv hollow bodies such as cast iron automotive cylinders by first heating these surfaces with ordinary oxyacetylene or similar burners, and then rapidly cooling the cylinders by submerging them in a tank of hardening liquid. This hardening method suffers from the drawback that'while the lower portion of the cylinder is quenched in water, there is formed above the water a socalled "closed space" and the burners such as oxy-acetylene do not function satisfactorily in such spaces. Generally speaking, no attempt in either of these directions has been found satisfactory. both because of diflicultics inherent in the elaborate apparatus required, the physical properties of the metals used, and because of the relatively high expense involved.

Among the objects of the present invention are: to provide an improved method of hardening surfaces of metal bodies: to provide an improved method of hardening cylindrical surfaces of metal bodies; to provide an improved method of hardening inner surfaces of cylinders of internal combustion engines and other hollow metal bodies; to provide an improved apparatus for hardening surfaces of metal bodies: and to .provide an improved apparatus for hardening This a It has also been proposed to pplication July 13, 1938,

accordance with this invention there is provided an apparatus for and methodof hardening the inner wall surface of such hollow metallic bodies which comprises progressively heating successive portions of said wall surface to a temperature above its critical range in a manner which tends to concentrate the zone of heat application to a relatively'narrow circumferential portion, and establishing a steep temperature gradient in said wall surface by producing a rapid dissipation of heat into the mass of said metallic body. V

In' accordance with the principles of this invention, a surface of a metal body may be hardened by maintaining said surface in a vertical position, heating successive horizontal zones of the surface beginning at the lower end thereof, and cooling successive heated horizontal zones by directing a cooling medium against the same, such as in the form of cooling jets, the heating and cooling progressing concurrently upwardly along said surface. It is advantageous to use a liquid cooling medium because then the'liquid of the cooling jetsruns downwardly by gravity along the treated lower portions of the surface after the liquid impinges against the highly heated surface, and thus further cools the treated surfaces and also is quickly and simply removed from the vicinity of the heating medium. The successive horizontal zones may be heated by a row of heating jets directed sub stantially perpendicularly against the surface,

and, since the surface is preferably maintained in a substantially vertical position, the rising heat from the jets will tend to preheat untreated higher portionsof the surface, while the liquid of the cooling jets will flow downwardly by gravity alongthe surface and thereby avoid interference with the heating jets. In addition, a substantially horizontal movement of the heating and cooling jets with respect to the surface may also be employed during the relative vermanufacture of hollow metallic bodies such as cylinders of internal combustion engines, and in cooling jets of heating flames, the hollow metal body is maintained open at both ends -'so that the current of air flowing through the body will provide air for secondary combustion ofthe heating flames. In hardening a cylindrical surface,

a relative rotational movement between the heating and cooling jets and surface 'may be effected concurrently with the relative vertical movement between the heating and cooling jets and surface, the relative vertical movement being substantially parallel to the surface.

The novel and characteristic features of this invention are set forth with particularity in the appended claims. The invention itself, however,

both as to its organization and its mode of operation, together with additionalobjects and advantages thereof, may be better understood from the following description of a specific embodiburners.

"Referring now' more particularly to 1, a

cylinder block l0, comprising a plurality of cylin-,

ders II is mounted on a suitable hollow support IS, in such a manner that air may freely enter and escape through the openings ll of the cylinder block coating. The water jackets 80 in th'e cylinder block) may be filled with a cooling medium, in order to facilitate the production of a steep temperature gradient and consequently a rapid cooling and quenching of the metal portionst undergoing the, surface hardening treatmen Situated partly above the cylinder block 18 is a hollow shaft'lt, provided at its lower end with a star-shaped burner head. I! having aplurality of radiallyextending nozzles 28 at its periphery. The shaft 18 comprises a longitudinal mixing passage for two gases entering throughthe hose lines I8 and I8, respectively, and a passage for conducting a cooling medium; from the supply line 20 towards the burner head I! and thencefto the discharge line 2|. Means are also provided toward the lower end of the burner and above the nozzles 28 for preventing th rapid upward escape of the heat generated by the nozzles 28, i. e. a baffle plate or screen 22. The general nature and function of this plate is described in more detail in connection with Fig. 2.

The longitudinal axis of the shaft 16 is inv substantial alignment with the longitudinal axis of the cylinder to-be treated. A suitable mechanism consisting of motor 8| and worm gear 82 may be provided to impart an oscillatory or rotar motion to the shaft l8 and to th burner head [1. Means may also be provided, as shown at 33 and 34, for producing a vertical motion' of the burner within the cylinder, substantially along the vertical axis of the latter, or for disengaging the burner head entirely from the interior of the cylinder, Alternatively, relative motion between the cylinder block l0 and the whole burner assembly may be effected by the vertical displacement of the cylinders with ref-' erence to the burner head.

Fig. 2 shows a longitudinal enlarged scale section through a modified type of burner. Above the conical nozzle head 21 of the burner there is secured an exchangeable conical baffle plate or screen 22. The diameter of the base of this baflle is larger than that of the base of the conical nozzle and slightly smaller than the inner diameter of the cylinder under treatment. The purpose of this baflie plate is two-fold: first, it confines and localizes the point of application of the heating flames, and second, when mounted above the nozzle head, it causes a down-draft of the surrounding cold air toward the heated portions and thus produces sudden cooling or air-quenching.

en using burners of the type illustrated in Figs. 1 and 2, the heat treating operation may be effected by moving the burner and cylinder block relatively to each other so that the burner gradually descends from above into the cylinder. Conseguently, the burning gas, escaping under substantial pressure from the discharge openings of the nozzles, will progressively h'eat annular zones on the inner surface of the cylin der. Due to the intense heat generated by the flame striking directly a comparatively small portion of the entire inner surface area of the cylinder, this portion will be heated very rapidly, and to a sufiicient depth, to 'a temperature above the critical point, and thereby cause some of the carbon to go into solid solution which, upon rapid cooling, will form a hard metal layer upon the inner surface of the cylinder.

Thisrapid cooling is achieved, at least partly, by maintaining the temperature of the main body of the cylinder block well below about 700 0. Due to heat conduction from the directly heated surface portion into the relatively cold 1 mass of the surrounding metal, a rapid decrease of temperaturepf the annular zone covered by the flame will result immediately after the flam is removed from such zone. Inasmuch as the flame moves progressively with reference to the inner wall of the cylinder, the directly and consecutively heated annular zones will, in turn,

od of keeping the surrounding metal at a rela-- "tively low temperature and using merely the temperature difference within an otherwise homogeneous mass of metal for creating the desired steep temperature gradient at the treated surface will tendto produce a cylinder block which, is more free from internal stresses than blocks, for example, which after heat treatment are quenched by submersion in a quenching fluid, while at the same time the main object of such treatment, 1. e. creating a uniform surface on the inner wall of the cylinders of great comparative hardness, is attained to a desired degree.

Instead of employing a conical burner such as in the arrangement shown in Fig. 2, it may be of advantage to use an inverted conical burner, as shown in Fig. 3, and to begin the heat'treating operation at the lower end, of the cylinder,

the burner in that case moving upwardly with reference to the cylinder during the treatment. The effect of using an inverted burner will be that an upwardly directed draft is created in the ylinder and that the cool air enters from the bottom following the direction of the natural draft. The combination of the forces from the draft caused by the-burner, and from the natural draft, tends to increase-the velocity of the flow of air.through the cylinder. -A heat resisting baflle is provided at the burner in the ,arasoe that it'is possible to use a grade of cast ironwhich is sufllciently soft to be easily machinable,

'since the desired wear characteristicsmay be imparted to such a material by the subsequent hardening operation. In contra-distinction to this it has been necessary heretofore to use a same manner as described above, in this modiflcation, howevervpreventing the flames in the upper section of the cylinder from heating too rapidly the cool .air entering the lower from below.

section One of the important features in this method is to insure not only a very rapid heating of consecutive annular zones of the inner surface of the cylinder, but at the same time a heating which is uniform along theentire periphery of such zone. To accomplish this uniform heating, a rotary or oscillatory motion around the longitudinal axis of the shaft l6 may be imparted to the burner H as described above. In the event that for anyreason the heat intensity ofthe conical flame should not be the same at each point of the periphery, the'rotary or oscillatory motion of the burner, and consequently of the flames, will tend to equalize any difference in the amount of heatreceived from the flame by any definite point of the heated annular zone, inasmuch as each point of the heated zone will receive its heat not from one single corresponding point of the flame, but successively from a plurality of such points so that any intensity" differences will be averaged and thus equalized. When practicing this embodiment of theinvention, in lieu of the conical burner described above, a burner with a plurality of radially arrelatively hard cast "iron in order to obtain the .wearing properties which are desired in practical vention may be applied generally to the hardening of vertically disposed metal surfaces, and

particularly to the hardening of vertically dis-' posed curved surfaces such as the inner cylindrical surfaces of metal bodies as.wel1 as the outercylindrical surfaces of metal bodies, and

also to inner surfaces of hollow bodies, other than cylinders of internal combustion engines. It will ner periphery beneath'the heating jets, providing an upward helical motion of the heating and ranged nozzles may preferably be used. An example of such burner having 8 nozzles is represented in Figure 4. The nozzles 28 are. preferably so constructed as to generate flames of a high intensity, which, when the burner oscillates or rotates, will heat an annular zoneon the inner wall ofthe cylinder and will thus impart heat of high intensity uniformly to all points of the annular zone. A heat baffle 29 is secured below the nozzles, in case of an upwardly progressive motion. Should it be found preferable to carry out the heating operation'in a progressive downward motion, the heat resisting batlle may be secured above the radial nozzles, in order to prevent a too rapid heating of the cool air entering from above.

In cases where it is desired to secure a more rapid quenching than air quenching and/or heat conductivity quenching, an apparatus such as disclosed schematically in Figs. 5 and 6 may be used. In accordance with this modification of the invention, a very drastic cooling is obtained by providing means, preferably at the rear side of the bafiie plate, for directing aspray of cold cooling jetswith respect to the tubular chamber, and passing air upwardly through thetubular chamber past the heating and cooling jets.

. 2. A process ofsubstantiallyuniformly hardening an interior metal surface of a tubular chamber openat both ends, which comprises progressively applying high temperature heating flames to successive annular zones of said surface; progressively applying a'quenching medium to such heated zones; and maintaining said chamber open at both ends during such heating and quenching so as to permit flow into Y and through said chamber of air for secondary combustion of said heating flames.

water or cold compressed air against the metal wall, as shownat 5i and BI. This spray mechanism is preferably adapted to follow the relative movement of the; burner in its axial direction,

and may also be arranged to follow the rotary motion of the rotary or oscillatory type of burner where such is used. V As illustrative of the results which may be accomplished by the use of the process described above, the hardness of the surface in an ordi- 3. Aprocess of substantially uniformly hardening an interior metal surface of a tubular chamberopen at bothends and disposed substantially vertically, which comprises progressively applying a high temperature heating medium to successive annular zones of said surface; progressively applying a quenching medium to such heatj ed zones; and maintaining said vertically disposed chamber open at both ends during such heating and quenching so as-to induce a draft of air therethrough along said surface.

4. A process as set forth in claim 3, in which the application of said heating medium is started adjacent the lower-end of said surface and progresses upwardly.

q 5. A process as set forth in claim 3, in which the quenching medium is a liquid and is applied nary cast iron cylinder has been increased from I 160 to approximately 350 Brinell.

A further advantage of this method of' hardening cylinders of internal combustion engines is closely following the application of said heating medium and discharges through the open lowerend of said chamber.

6. ln'the methochof securing beneficial changes in the constitution of the inner surface of a tubular ferrous b0dy,'the steps comprising maintaining said body sufficiently open at both ends to permit a flow of air therethrough, directing heat ing jets against-theinner surface, and screening a portion of the interior of the tubular body to form an annular passage adjacent the inner sur- It will be evident that the method of this in-- face so as to direct a stream of air against the heated surface.

7. The methodof securing beneficial changes in the constitution of the inner periphery of a tubular ferrous body which comprises maintaining said body sufficiently open at both ends to permit a flow of air'therethrough, directing heating jets generally radially against the inner periphery of the tubular body, screening a portion of the interior of the tubular body at a zone adjacent to the heating jets to form an annular passage adjacent to the periphery so as to direct a stream of air against the heated surface, providing relative rotary movement of the jets with respect to the periphery, and providing relative movement between the jets and the periphery along the axis of the tubular body.

8. In the method of securing beneficial changes in the constitution of the inner surface of a tubular ferrous chamber open at both ends, the step comprising projecting heating jets against the in ner periphery of the tubular chamber at an angle thereto to promote the flow of air through the tubular chamber.

9. In the method of securing beneficial changes in the constitution of the inner surface of a tubular ferrous body, the steps comprising mounting the tubular body in a generally vertical position, and projecting heating jets upwardly against the inner periphery of the tubular body to promote the natural flow of cooling fluid through the tubular body. a

10. In the method of securing beneficial changes in the constitution of'the inner surface of a tubular ferrous body open at bothends, the steps comprising projecting a hollow conical jet of heating gas against a peripheral zone of the tubular body to promote the flow of air therethrough, and rotating the jet to equalize the distribution of heat about'the peripheral zone.

11. Apparatus for heat treating the inner surface of a hollow metal body comprising heating means adapted to travel along and in spaced relationship with the interior surface of said a baffle associated with said heating means for concentrating heat upon peripheral annular sectionsof said inner surface, said baffie corresponding in shape to and being spaced from said inner surface to provide an annular air passage therearound so as to permit a current of air to flow therethrough so as to cool the heated portions; and means for effecting a relative movement of said heating means and said bafile longitudinally with respect to the interior surface of said body.

12. Apparatus for heat treating the inner surface of a hollow metal body as defined in claim 11, including a spraydevice operatively associated with said heating means and bafiie and said movement effecting means in such a manner as to direct a stream of fluid quenching medium upon the heated portions to augment the effect of such air and thereby cool the heated portions rapidly.

13. Apparatus for obtaining beneficial changes in the constitution of the inner periphery of a tubular ferrous body comprising a heating head, means for mounting said body in substantially a vertical position, means associated with said.

heating head .for projecting a heating jet upwardly against said periphery, and means for providing relative axial and rotational movement between said jet and said body whereby successive peripheral portions of said body are raised to a high temperature, the upward projection of said jet promoting the flow of air through said tubular body.

14. Apparatus as defined in claim 13 including a baflie adjacent to said heating jet and restricting the-passage through the tubular body to a narrow annular space adjacent to the heated peripheral portion, whereby the air flowing upwardly through the tubular body is constrained to pass in close proximity to the heated peripheral portion.

' 15. A method of hardening a surface of a metal body comprising progressively applying a high temperature heating medium locally to successive substantially horizontal zones of said surface while maintaining all portions of said surface in a substantially vertical position and while maintaining unobstructed the entire space adjacent and along said surface and above the points ofapplication of said heating medium to permit a free and unobstructed rise of heated gases upwardly along said surface from said points of heat application; screening a portion of the space beneath said heating medium to form an air passage adjacent said surface through which a stream of relatively cool air is directed against said surfa'ce; and directing a cooling liquid against successive zones so heated, said heating medium and cooling liquid being initially applied adjacent the lower end of said surface and the heating and cooling progressing upwardly concurrently so that the heated gases rising from the points of application of said heating medium preheat untreated higher portions of said surface and the cooling liquid runs downwardly by gravity along the treated lower portions of said surface after such liquid impinges against said surface. l

16. A method of hardening a surface of a metal body comprising directing a row'of high temperature heating flames against a substantially horizontal zone of said surface while maintaining all portions of said surface in a substantially vertical position and while maintaining unobstructed the entire space adjacent and along said surface and beneath the points of application of said heating flames to permit a free and unobstructed rise of heated gases upwardly along said surface from all points of application of said heating flames and to permit a flow of air to said flames from beneath for secondary combustion thereof; directing a row of liquid cooling jets against a substantially horizontal zone of said surface beneath said heating flames; and effecting a relative movement upwardly substantially parallel to said surface and also horizontally between said body and both said heating flames and said liquid cooling jets, said heating flames and said liquid cooling'jets being initially applied adjacent the lower end of said surface so that heating and cooling progresses upwardly concurrently with heated gases rising vertically along said surface, from the points of application of said heating flames, to preheat untreated higher portions of said surface, and cooling liquid' running downwardly by gravity along the treated lower portions of said surface after impinging against said maintainingunobstructed the entire space adjacent and along said surface and above the points of application of said cooling jets to permit a free and unobstructed rise of heated gases upwardly along said surface from said points of heat application and to permit a flow of air to saidheating flames for secondary combustion thereof; effecting motion of said heating jets and cooling jets relatively to said body upwardly and substantially parallel to the axis of said surface, to progressively heat-and quench successive portions of said surface; and maintaining the axis of said surface in a substantially vertical position during such relative motion so as to cause said liquid to flow downwardly by gravity along said surface after impinging agalnst' the latter and thereby avoid interference of said liquid with said heating jets, and also to cause the heated gases rising from the points of application of said heating flames to preheat higher untreated por- ''tions of said surface;

, adjacent to but beneath the horizontal zone to which said heating medium is applied; means for effecting relative movement, upwardly substantially parallel to said surface and also transversely of the vertical dimension of said surface, between said body and both such means for applying the heating medium and cooling liquid so that said heating medium and cooling liquid will .be initially applied adjacent the lower end of said surfaceand the heating and cooling will progress upwardly concurrently so that the rising heat from said heating medium will tendto preheat untreated higher portions of said surface and the cooling liquid will run downwardly by gravity along the treated lower portionsof said surface after such liquid impinges against said surface; and baiile means disposed beneath said heating means but above said cooling means and corresponding in shape to said surface but spaced therefrom so as to form an air passage adjacent said surface, said batlie means serving to direct toward said surface,'at and immediately below said heating means, a current of relatively cool air induced to flow upwardly by the heated gases rising upwardly along said surface from said heating means.

19. Apparatus for hardening a cylindrical surface of a metal body comprising, in combination, means for maintaining said surface with its axis in a'substantially vertical position; means for directing an annular row of heating jets substantially radially against said surface; means for directing an annular row of liquid cooling jets substantially radially against said surface and adjacent to but beneath said heating jets; means for advancingboth of such jet directing means upwardly relatively to, and substantially parallel to, said surface, to heat and quench successive portions of said surface while the rising heat from the heating jets preheats higher portions of said surface and the cooling liquid runs downwardly by gravity along treated lower portions of said surface after such liquid impinges against said surface; and baflle means disposed below said heating .jets but above said cooling jets and spaced from said surface to provide an annular air passage adjacent said surface, said baffle means serving tov direct toward said surface, at and immediately below said heating jets, a current of relatively cool air induced tofiow upwardly by the heated gases rising upwardly along said surface from said heating jets.

AUGUSTUS B. KlN ZEL. 

